Problem: $\dfrac{4}{6} - \dfrac{9}{2} = {?}$
Explanation: $ = {\dfrac{4 \times 1}{6 \times 1}} - {\dfrac{9 \times 3}{2 \times 3}} $ $ = {\dfrac{4}{6}} - {\dfrac{27}{6}} $ $ = \dfrac{{4} - {27}}{6} $ $ = -\dfrac{23}{6}$